Yield performance of 14 novel inter- and intra-species Miscanthus hybrids across Europe

Miscanthus, a C4 perennial rhizomatous grass from Asia is a leading candidate for the supply of sustainable biomass needed to grow the bioeconomy. European Miscanthus breeding programmes have recently produced a new range of seeded hybrids with the objective of increasing scalability to large acreages limited by current clonal propagation. For the EU-GRACE project, new replicated field trials were established in seven locations across Europe in 2018 with eight intraspecific M. sinensis hybrids (sin × sin) and six M. sacchariflorus × M. sinensis (sac × sin) from Dutch and UK breeding programmes, respectively, with clonal Miscanthus × giganteus. The planting density of the sin × sin was double that of sac × sin (30,000 & 15,000 plants ha⁻¹), creating commercially relevant upscaling comparisons between systems. Over the first 3 years, the establishment depended on location and hybrid. The mature sin × sin hybrids formed tight tufts of shoots up to 2.5 m tall which flower and senesce earlier than the taller sac × sin hybrids. Following the third growing season, the highest yields were recorded in Northern Italy at a low altitude (average 13.7 (max 21) Mg DM ha⁻¹) and the lowest yielding was on the industrially damaged marginal land site in Northern France (average 7.0 (max 10) Mg DM ha⁻¹). Moisture contents at spring harvest were lowest in Croatia (21.7%) and highest in Wales, UK (41.6%). Overall, lower moisture contents at harvest, which are highly desirable for transport, storage and for most end-use applications, were found in sin × sin hybrids than sac × sin (30% and 40%, respectively). Yield depended on climate interactions with the hybrid and their associated planting systems. The sin × sin hybrids appeared better adapted to northern Europe and sac × sin hybrids to southern Europe. Longer-term yield observations over crop lifespans will be needed to explore the biological (yield persistence) and economic costs and benefits of the different hybrid systems.